(literally “undisturbed”). A drug used to control anxiety, tension, and overactivity without causing somnolence—a tranquilizer. See tranquilizers, chemotherapy.The get of focusing on a specific portion of the total stimulation impinging on the organism.Attention is probably the most common of all psychological functions. Whenever we engage in any activity, we focus on certain aspects of the situation and disregard all others. The student in a library directs his attention to the book in front of him and ignores (more or less) a host of other stimuli: tables, chairs, people, sounds from the room and the street outside, the pressure of his clothing, the kinesthetic sensations of sitting and crossing his legs.all these, and more, are screened out and occupy the “margin” rather than the “focus” of attention. Reading a book is therefore a selective process which limits the student to certain aspects of his environment, but it is interesting that at any moment a change in the field of stimulation—a familiar voice, a sudden pain in the stomach —may cause a shift in attention, and what was marginal a moment ago will now be central. This brings up the question of identifying the variables or determinants involved in attention.The internal determinants of attention include past experience, ongoing behavior, and the individual’s physiological condition. First, past experience and habitual attitudes have a great deal to do with structuring our perceptual world. We notice things that have a meaning for us. The artist will approach a country scene with a different “internal context” from a farmer, and will “register” certain colors or shapes or patterns which the farmer completely overlooks. But the farmer, too, will see the scene in the light of his own experience.Second, ongoing behavior, or “activity in progress,” has a great effect on what we notice. As the runner poises himself to hear the starting gun and gets set for a fast takeoff, he shuts out the sights and sounds of the crowd. And as he runs the race, he may not attend to a cut or bruise he receives in jumping over a hurdle—but once the race is over he may realize that it is extremely painful. A special area of the brain, the reticular formation, appears to be involved in shunting aside stimulation which is not important for ongoing behavior.Third, the physiological condition of the organism has much to do with selective attention. The hungry man notices more restaurants than the man who has just eaten, and a person who is dying of thirst in the desert may even see a mirage. McClelland and Atkinson (1948) kept groups of subjects hungry for one, four, and sixteen hours, respectively, then had them look at meaningless smudges on a dimly lighted screen. The subjects identified the smudges as articles of food in direct proportion to the time that had elapsed since they had last eaten.The “external determinants” of attention can be dealt with summarily since most of them are illustrated under another topic. See ADVERTISING RESEARCH. First, repetition of a political slogan, trade name, or important point in a lesson usually captures attention, though it may defeat itself if it is overdone and becomes monotonous. Repetition with variation, or repetition in another sense modality, will often accomplish the purpose better. Second, sheer size may arrest attention, and is especially important in highway signs and advertisements. However, it does not operate by itself, since other factors such as clarity and color are usually involved. Third, change and movement have great attention value not only because we get bored with sameness, but because our sense organs actually fail to register when the level of stimulation remains the same. The changes may occur in place, color, speed of movement, or simply be an on-off affair as in some illuminated signs. See SENSORY ADAPTATION.Fourth, intensity of the stimuli is an important factor, though this is a relative matter: a blowout occurring at Times Square will attract less attention than a blowout on a quiet street. Fifth, novelty is closely related to change but adds the dimension of the unusual—for example, “trick” photos, or animals appearing to mouth the words of a commercial. Sixth, contrast: the sharply contrasting color of the hunter’s red shirt keeps others from shooting him; the high-pitched Navy whistle is designed to stand out from all other sounds on the ship. Camouflage, on the other hand, is designed to eliminate attention-getting contrasts in color and shape.The postural adjustments involved in attention have been studied by many investigators. In general, their main purpose is to bring the receptors into maximal contact with the stimulus: we “sit up and take notice” or “sit on the edge of our seat.” At the same time we may attempt to cut out competing stimuli, as in closing our eyes at a concert. The muscle tensions involved in attending can be measured, and it has been found that complex tasks which require precise attention use more energy than simple ones (Morgan, 1916).Francis Galton was probably the first to record the muscular changes that take place in attention and other forms of mental activity. He devised an instrument called the automatograph consisting of a small plate which could be moved over a smooth glass surface with a minimum of friction. By this means he was able to record slight changes in the movement of the hands, showing, for example, that when a subject thought about a distant building, or added numbers, the hands involuntarily moved in the appropriate directions. This is the principle on which “hand readers” operate, and probably palmists as well, although palmists may also be sensitive to pulse and perspiration changes and more general behavioral reactions. See EXTRASENSORY PERCEPTION.William James also made an interesting contribution to this subject. He suggested that the extraneous and highly individual motor activities that occur in attending—knitting the brows, pacing, etc.—help to dissipate incoming stimuli which might distract us from the task at hand. As evidence he cited the story that Walter Scott became the top student in his class by cutting off the jacket button the star student always played with as he recited. Deprived of this motor outlet the boy was distracted by irrelevant stimuli and could not maintain his intense concentration.A number of studies have also been made of the fluctuation of attention. In an early experiment, Billings (1914) asked subjects to rivet their eyes on a specific visual object and report when they first noticed their attention wandering. The average time for this single act of attention was only two seconds, with a variation from .1 second to 5 seconds for different subjects. These results agree fairly well with measurements of the time taken by darting eye movements that occur when we explore a picture visually. Buswell (1935) showed that we make about four fixations per second when we observe a general visual field without any particular purpose in mind. Some psychologists believe the waxing and waning which occur when we listen to a ticking watch held at a distance from our ear is an example of fluctuation of attention, but others attribute it to changes in nerve activity.How well can we attend to two or more things at once? Here again many of the important experiments were performed some time ago. Paulhan (1887) found it possible to write one familiar poem while reciting another or while performing simple multiplication. However, he found that even these simple and familiar operations would always interfere with the performance of tasks that involve any degree of difficulty. Mager (1920) and Pauli (1924) experimented with simultaneous tasks of an extremely simple nature, such as counting three to six short lines and telling which of two pressures applied to the fingers was the stronger. They found that both judgments were correct in only 12 per cent of cases, neither was correct in 28 per cent and one correct in 60 per cent. These and other experiments indicate that when two tasks are presented simultaneously, one or both will suffer in efficiency. Westphal (1911) and Schorn (1928) have shown that in general the best way to handle two simultaneous tasks is to combine them, if possible, into a single co-ordinated performance. There is wide individual variation in this ability, and for this reason people who are called upon to do many things at once—for example, telephone operators and pilots—are frequently given special tests to see if they can handle them.